This invention relates generally to blasting apparatus. More particularly, this invention relates to blasting apparatus having deflectors or diverters to direct airflow and the flow of blasting medium.
Many industrial and other processes use blasting to clean or finish metal and other surfaces. Generally, particles are propelled to impinge against the surface at high speed. Typically, a gas or liquid carries the particles. Alternatively, the particles may be thrown centrifugally by a wheel or similar means.
The particles may be abrasive and non-abrasive and are usually in the shape of shot or grit. Blasting media vary depending upon the particular application and include glass beads, aluminum oxide, steel shot, plastic, and virtually any material having a suitable size and mechanical properties. The particle size depends on the application and the media. The type of particle often describes the type of blasting. For example, shot blasting uses shot as the blasting media. The shot may be made of steel or another material.
The impingement of the particles modifies the surface condition. As a result, blasting is used in many different applications. For example, sand may be removed from castings. Scale may be removed from forgings and other iron and steel products. The flashings and other joining edges may be removed from die castings, plastic parts, and electric circuits. Surfaces may be prepared for painting or other coating applications. Burrs, edges, and other surface imperfections may be removed. Surface characteristics may be altered such as in shot peening, where blasting increase surface stresses thus improving the fatigue life of the material. There are numerous other applications for blasting processes.
Blasting equipment depends upon the application, the blasting media, and similar factors. Generally, a blasting cabinet encloses a work piece during the blasting operation. The blasting cabinet typically has a rectangular structure and is made of metal. The blasting cabinet may be part of a larger process, where the work piece or part is moved on a conveyor into the blasting cabinet. Alternatively, a robotic arm or similar mechanical device may place the work piece into the blasting cabinet. The blasting cabinet may have a rotating or movable table to reposition the work piece during the blasting process.
A propelling device directs the blasting medium into the blasting cabinet and against the surface. The propelling device may be a pressure blasting nozzle system, a suction blasting nozzle system, or a centrifugal wheel, all of which are well known in the art. In the nozzle systems, the propelling device propels air and the blasting medium through a blasting nozzle. The air and medium mixture is accelerated through the nozzle, into the blasting chamber, and against the work piece. The blasting medium ricochets off the work piece and the wall of the blasting cabinet.
The blasting medium usually collects at the bottom of the blasting cabinet. A separator separates the blasting medium from the fines, sand, and other debris from the work piece. A medium-return system returns the blasting medium to the propelling device. Additional blasting medium may be added at that time. A dust collector typically removes particle fines and contaminants from the air before air is released into the environment.
Many blasting devices have a deflector to control the medium flow. The deflector also may be used as a diverter to direct the medium flow against the work piece. The deflector is position inside or at the end of the nozzle. A typical deflector is made of metal and has a flap-shape to cover the nozzle opening. The deflector has a pin or similar rotating means passing through the center of the flap-shape. The deflector rotates about the pin to control the airflow and to direct the medium blasting against the work piece.
Deflectors typically require frequent maintenance and replacement. The nature of the blasting medium and air mixture wears and often warps the deflector. The virtually constant pelting of the deflector by the blasting medium causes the deflector to fail. Prior to failure, the deflector may become misaligned or otherwise distorted. A suitable deflector position for a new deflector may no longer be suitable for a worn deflector.
Accordingly, there is a need for a blasting device having a deflector that withstands the wear warping from the blasting medium.
The invention provides a blasting apparatus with a dual structure deflector. The dual structure deflector provides a rigid and impact resistant configuration, which controls the airflow and flow of blasting medium more accurately and for longer periods than conventional deflectors.
In one aspect, the blasting apparatus includes a blasting cabinet for housing a work piece, a nozzle, a propelling device, and a blasting medium holding unit. The blasting cabinet may have a grating structure, a separator, and a dust collector.
In use, a work piece rests upon a grating structure near the bottom of the blasting cabinet. The propelling device directs air and blasting medium via a blasting path against the work piece. After striking the work piece, the spent blasting medium and material from the work piece pass are collected in a separator or similar structure. The air may pass through a dust collector.
In one embodiment, the dual structure deflector is position in the blasting path to control the airflow and the flow of the blasting medium. The dual structure deflector includes an interior structure, an exterior structure, and a tubular support. The tubular support may extend radially through the center of the interior and exterior structures. In one aspect, each tubular support mounting section has a cavity for receiving a mounting pin. The mounting pins extend through the wall of the nozzle and insert into the cavities of the mounting sections. The dual structure deflector may rotate about the tubular support, thus opening and closing the nozzle.
The following drawings and description provide additional advantages and benefits of the invention. More advantages and benefits are obvious from the description and may be learned by practice of the invention.